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Li-ion secondary battery formation method

A chemical formation method and secondary battery technology, applied in secondary batteries, secondary battery repair/maintenance, secondary battery charging/discharging, etc., can solve problems such as poor cycle performance of lithium-ion secondary batteries, and achieve good cycle performance , Uniform charge state, prolong life effect

Active Publication Date: 2008-07-02
BYD CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0005] The purpose of the present invention is to overcome the disadvantages of poor cycle performance of lithium-ion secondary batteries obtained by existing chemical formation methods, and to provide a chemical formation method for lithium-ion secondary batteries that make batteries have good cycle performance

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0019] This embodiment illustrates the formation method of the lithium ion secondary battery provided by the present invention.

[0020] 1. Preparation of battery

[0021] (1) Preparation of positive electrode

[0022] Dissolve 30 grams of polyvinylidene fluoride (PVDF) in 450 grams of N-methylpyrrolidone (NMP) solvent to prepare a binder solution, and then mix 940 grams of LiCoO 2 Add 30 grams of acetylene black powder into the above solution, fully stir and mix evenly to prepare positive electrode slurry;

[0023] The positive electrode slurry was evenly coated on both sides of aluminum foil with a thickness of 25 microns, heated and dried under vacuum at 150°C for 1 hour, rolled, and cut into pieces to obtain a positive electrode with a length of 550 mm × width of 43.8 mm × thickness of 130 microns, each positive electrode Contains 8 grams of LiCoO on 2 .

[0024] (2) Preparation of negative electrode

[0025] 950 grams of graphite, 20 grams of carbon fiber and 30 gram...

Embodiment 2

[0035]Lithium-ion secondary batteries were prepared according to the method described in Example 1, except that they were charged to 3.1 volts with a current of 0.08 coulombs, and then charged and discharged 4 times at 3.1-3.7 volts after being left for 5 minutes, with a charge current of 0.08 coulombs and a discharge current of 0.3 coulomb. Continue to charge the battery with a constant current of 0.3 coulombs to 4.05 volts, leave it for 6 minutes, then cycle charge and discharge twice at 4.05-4.25 volts, charge current 0.08 coulombs, discharge current 0.8 coulombs, and finally charge the battery with a constant current of 0.08 coulombs to After 4.25 volts, the formation is completed, and the liquid injection hole is sealed to obtain the lithium-ion battery A2 after formation.

Embodiment 3-4

[0037] Lithium ion battery A1 and A2 after the formation that embodiment 1-2 obtains, use BS-9300 (R) secondary battery performance detection device to carry out cycle performance test, the battery after formation is with 300 milliampere (0.3 coulomb) constant Current charging to 4.2 volts, charging cut-off current 20 mA. Then it was discharged to 3.0 volts at 500 mA, and the initial capacity of the battery was measured. Repeat the charging and discharging process with 300 mA (0.3 coulomb) constant current to 4.2 volts; then discharge to 3.0 volts with 500 mA (0.5 coulomb) and record the 10th, 50th, 70th, 100th, 150th, 200th, 250th , 300 cycle end capacity, and calculate the battery capacity retention rate according to the following formula:

[0038] Capacity retention = end-of-cycle capacity / initial capacity×100%.

[0039] The results of capacity retention are shown in Table 1.

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PUM

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Abstract

The invention relates to a formation method of a lithium iron secondary battery. The method is that the battery is carried out a formation under the formation temperature; the continuous current is used for charging to V1 volt; the circulation continuous current is used for charging and discharge at least once under the volt of V1 to V2; the continuous current is used for charging to V3 volt; the circulation continuous current is used for charging and discharge at least once under the volt of V3 to V4; a relation is existed in the voltages: voltage V1 < voltage V2 < voltage V3 < voltage V4. The invention, through providing the formation method for battery, can solve the impact to the battery charge from the gas persistence and obtain the even and stable SEL film as well as cause the battery to have a good circulation performance.

Description

technical field [0001] The invention relates to a method for forming a battery, in particular, the invention relates to a method for forming a lithium ion secondary battery. Background technique [0002] The formation step of lithium-ion rechargeable batteries is an important stage in the manufacture of batteries. The formation is related to the quality of the battery's capacity, cycle life, and safety performance. Formation is the process of charging a battery for the first time. There are mainly two ways of formation of the existing lithium-ion secondary batteries, sealed formation and open formation. Sealing formation is to seal the liquid injection hole after the electrolyte is injected, and then perform battery formation. During the formation process, gases such as ethylene, diethylene, phosphorus fluoride, and hydrogen fluoride are generated. These gases accumulate inside the battery and cause battery expansion. , the casing bulges, deforms, and even causes the batte...

Claims

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Application Information

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IPC IPC(8): H01M10/38H01M10/40H01M10/44H01M10/058
CPCY02E60/122Y02E60/10Y02P70/50
Inventor 陆楠
Owner BYD CO LTD
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